In the manufacture of an electronic device such as a semiconductor device, a plasma processing apparatus is used. Generally, the plasma processing apparatus includes a processing vessel and a mounting table. The mounting table holds a processing target object mounted thereon and is provided within the processing vessel. In the plasma processing apparatus, the processing target object is mounted on the mounting table and is processed by plasma of a processing gas, which is generated within the processing vessel.
In the aforementioned plasma processing apparatus, in order to improve processing uniformity over an entire surface of the processing target object, a focus ring may be provided on the mounting table to surround an edge of the processing target object. The plasma processing apparatus with the focus ring is described in Patent Document 1.
Patent Document 1: Japanese Patent Laid-open Publication No. 2012-049166
In the plasma processing apparatus, the focus ring as well as the processing target object is exposed to active species of molecules or atoms in the processing gas. Accordingly, the focus ring is consumed (worn) by performing a process on the processing target object. If an excessively consumed focus ring is used, the process on the processing target object is adversely affected. Thus, the excessively consumed focus ring needs to be replaced.
From this background, it is required to inspect the focus ring to figure out a consumption amount thereof.